Structure and Physiology of Blood Vessels
Uri Dinnar in Cardiovascular Fluid Dynamics, 2019
The arterial tree comprises of vessels of various length and diameter that successively branch into smaller vessels. When a specific internal organ, or arterial segment, is to be considered, the average dimensions should be studied very carefully. Classification of arteries is usually done by their size, however, another classification that is very frequently used, is by structure. The larger arteries leading from the heart and the first few branches are known as the elastic arteries, because of the large amount of elastin in them. Collagen fiber is a protein substance that appears in blood vessels as strings of fibers with a serpentine shape, and a certain degree of slackness. Mechanically elastin fibers behave very similar to rubber, and also their structure of long protein molecules with covalent cross-linkages resembles that of vulcanized rubber. The tunica intima consists of a single layer of endothelium with a thin layer of elastin and collagen fibers.
Determining Retinal Vessel Widths and Detection of Width Changes
Herbert Jelinek, Michael J. Cree in Automated Image Detection of Retinal Pathology, 2010
Detection of width changes in blood vessels of the retina may be indicative of eye or systemic disease. However, all fundus images, even those taken during a single sitting, are acquired at different perspective geometries, have different scales, and are difficult to manually compare side by side. This problem is increased for images acquired over time and is in no way lessened when different cameras are used as technology improves or patients change doctors. Indeed, even the method of image recording media has changed. In order to compare two images acquired at different times, automated techniques must be used to detect vessels, register images, and identify potential regions of blood vessel width change.
Experimental and Numerical Investigation on Simulating Nanocryosurgery of Target Tissues Embedded with Large Blood Vessels
W. J. Minkowycz in Advances in Numerical Heat Transfer, Volume 3, 2009
Cryosurgery, sometimes referred to as cryotherapy or cryoablation, is the use of extreme cold produced by cryogenic agents to destroy abnormal or diseased tissues. e application of cryosurgery includes treatment of many kinds of cancer and some noncancerous diseased tissues. Good results have been achieved in CONTENTS 7.1 Introduction 221 7.2 Experimental Procedures 223 7.2.1 Phantom Study 223 7.2.2 In Vitro Tissue Study 226 7.3 Numerical Modeling 228 7.4 Results and Discussion 231 7.4.1 Experimental Results 231 7.4.1.1 Phantom Experiments 231 7.4.1.2 In Vitro Tissue Experiments 240 7.4.2 Numerical Results 247 7.5 Conclusions 253 Acknowledgments 253 References 255 cryosurgical treatment of many types of tumors [1]. However, local recurrences at the site of ablation close to large blood vessels have been reported at rates from 5% to 44% or even higher [2,3]. In order to perform a successful cryosurgery for tumors embedded with large blood vessels, it is very necessary to understand the eects of large vessels on the temperature responses of biological tissues subjected to freezing [4-6].
Spatially Guided Angiogenesis by Three-Dimensional Collagen Scaffolds Micropatterned with Vascular Endothelial Growth Factor
Published in Journal of Biomaterials Science, Polymer Edition, 2012
Hwan Hee Oh, Hongxu Lu, Naoki Kawazoe, Guoping Chen
Successful regeneration of large and highly functionalized tissue and organs depends on the ability to guide blood vessel formation with three-dimensional scaffolds. Angiogenic growth factors have the potential to stimulate blood vessels in scaffolds. However, simply incorporating angiogenic growth factors in a random fashion may lead to uncontrolled blood vessel generation, which ultimately results in poor blood vessel network function and uneven growth of engineered tissue. To control and guide the formation of a blood vessel network in porous scaffolds, we prepared collagen sponges with micropatterned vascular endothelial growth factor (VEGF). VEGF was micropatterned in three-dimensional collagen sponges using micropatterned collagen/VEGF ice lines, which were prepared by a dispersing machine. The VEGF-micropatterned collagen sponges were implanted subcutaneously in nude mice. Following 6 weeks of implantation, the VEGF-micropatterned collagen sponges induced the formation of micropatterned blood vessel networks. More blood vessels were observed in the regions in which VEGF was immobilized than those without VEGF. The micropattern of VEGF determined the micropattern of the regenerated blood vessel network. The spatial immobilization of VEGF in three-dimensional porous scaffolds may be useful to stimulate guided blood vessel formation in a variety of tissue-engineering applications.
Morphological and Histological Evaluations of 3D-Layered Blood Vessel Constructs Prepared by Hierarchical Cell Manipulation
Published in Journal of Biomaterials Science, Polymer Edition, 2012
Michiya Matsusaki, Koji Kadowaki, Eijiro Adachi, Takeshi Sakura, Utako Yokoyama, Yoshihiro Ishikawa, Mitsuru Akashi
Three-dimensional (3D)-layered blood vessel constructs consisting of human umbilical artery smooth muscle cells (SMCs) and human umbilical vascular endothelial cells (ECs) were fabricated by hierarchical cell manipulation, and their basic morphology, histology and blood compatibility were evaluated in relation to the EC layers. For the hierarchical cell manipulation, fibronectin-gelatin (FN-G) nanofilms were prepared on the surface of SMC layers to provide a cell adhesive nano-scaffold for the second layer of cells. The layer number of blood vessel constructs was easily controllable from 2 to 7 layers, and the histological evaluation, scanning electron microscope (SEM) and transmission electron microscope (TEM) observations indicated a hierarchical blood vessel analogous morphology. The immunefluorescence staining revealed homogeneous and dense tight-junction of the uppermost EC layer. Furthermore, the nano-meshwork morphology of the FN-G films like a native extracellular matrix was observed inside the blood vessel constructs by SEM. Moreover, a close association between actin microfilaments and the nano-meshworks was observed on the SMC surface by TEM. The blood compatibility of the blood vessel constructs, 4-layered SMC/1-layered EC (4L-SMC/1L-EC), was clearly confirmed by inhibition of platelet adhesion, whereas the blood vessel constructs without EC layers (4L-SMC) showed high adhesion and activation of the platelet. The 3D-blood vessel constructs prepared by hierarchical cell manipulation technique will be valuable as a blood vessel model in the tissue engineering or pharmaceutical fields.
Expression of matrix metalloproteinase-9 (MMP-9) and blood vessel density in laryngeal squamous cell carcinomas
Published in Acta Oto-Laryngologica, 2011
Claus Wittekindt, Nebojsa Jovanovic, Orlando Guntinas-Lichius
Conclusion: In this study we found that inflammatory cells may be a source of MMP-9 in laryngeal cancer. MMP-9 was correlated with blood vessel density. MMP-9 may be a potential target to disrupt tumor neovascularization. Objective: To study the expression of MMP-9 in laryngeal cancer and determine a possible relation with blood vessel density. Methods: Immunohistochemistry was used for MMP analysis and for blood vessel detection in 83 laryngeal cancer samples. The density of blood vessels was analyzed with a stereological tool. Results: MMP-9 was detected in inflammatory cells. Positivity for MMP-9 correlated significantly with the grade of differentiation (p = 0.025). Expression of MMP-9 was not correlated with T stage, nodal metastasis, or tumor recurrence. The mean blood vessel density was 51.4 vessels/mm2. Specimens were more likely to exhibit higher density of blood vessels when MMP-9 expression was also present (p = 0.014).